Change-speed gear, especially for bicycles



July 11, 1939. E. BAUMGARTNER CHANGE-SPEED GEAR, ESPECIALLY. FOR BICYCLES 2 Sheets-Sheet 1 Filed Oct. 11, 1957 y 1939- s.. BAUMGARTNER CHANGE-SPEED GEAR. ESPECIALLY FOR BICYCLES Filed Oct. 11, 1937 2 Sheets-Sheet 2 Patented July 11, 1939 oFFIcr.

CHANGE-SPEED GEAR, ESPECIALLY FOR BIOYCLES Emile Baumgartner, Bienne, Switzerland Application October 11, 1937, Serial No. 168,489 In Switzerland November 16, 1936 2 Claims.

The present invention relates to a change speed gear for bicycles.

There are already change-speed gears known where the gear ratio between crankshaft and chain wheel may be changed by back-pedaling. In this case generally for each change one pair of change wheels in constant mesh is provided, whereof one Wheel is on the crankshaft and the other wheel on a countershaft. All Wheels of the countershaft are integral with each other. Spring controlled pawls located in radial bores of the crankshaft are used for changing the gear ratio, said pawls being put into or out of engagement with one of the change wheels during the back- 5 pedaling of said shaft by means of a cam shaft placed in an axial bore of the shaft.

These known mechanisms show certain disadvantages. Thus for instance in the case of three change-speed devices an immediate change 20 from the first to the third speed is not possible. It cannot be avoided to have first thrown in the intermediate second speed. Therefore the pedals instead of being operated only once must be operated twice, forwards and backwards, to obtain the 25 desired gear ratio. The structure of these change speeds is also such that the pawls operating the change are engaged sometimes only partly with their corresponding Wheels and are working in this position until the next change. These pawls 30 are therefore overstrained and break frequently. Also with the cam shaft, owing to the numerous cross and longitudinal bores which weaken the respective parts, occasional breakages occur.

It is the object of the present invention to 35 avoid all such disadvantages. The arrangement according to the present invention permits a direct switching in of the desired speed by a single back-pedaling whereby one or more intermediate speeds may be jumped. The form of the pawls 0 and their arrangement is such, that no bores of the crankshaft are needed and that the pawls come always into full engagement with their wheels.

The speed change according to the present in- 45 vention is remarkable in that each of the pawls comprises a shaft provided with two dogs, each shaft being sunk into a separate groove of the crankshaft, one of said dogs cooperating with his appertaining change wheel and the other dog being in operative'connection with a control disk, which, when the pedal shaft is back-pedaled, brings the respective dogs one after the other into or out of engagement with their appertaining 55 change wheels. 7

The drawings show as an example one embodiment of the invention in- Fig. 1 by a longitudinal section, in

Fig. 2 by across section on line II-II in Fig. 1, in

Fig.3 by a similar cross section as Fig. 2, but with parts in another position and in Fig. 4. by a cross section on line IVIV in Fig. 1.

The change speed shown is arranged for three speeds. l is the pedal shaft, 2 are the two cranks 10; integral with said shaft and 3, 4 and 5 are three gear wheels loose on said shaft and adapted in size to the intended three speeds, These gear Wheels are in constant mesh with three toothed rims 1a, 1b, 1c of an intermediate wheel 1 loose on the countershaft 8. The crankshaft l is journalled at one end in a ball bearing 2| and at the other end in the hub 5a of the gear wheel 5. This hub 5a is itself journalled in a ball bearing 22. Both ball bearings 2| and 22 are seated in the side walls 24, of a casing completed by a shell 23 and held together by bolts 26.

Equally spaced on the circumference of the crankshaft are three carrier pawls, each formed of a shaft 90, I00, I10 provided each with two 25 dogs 9a, 9b, lDa, [0b, Ila, Mb. The shafts 9c; Hlc, Ilc are lodged in three parallel longitudinal grooves la of the crankshaft and are journalled at one end in a collar [9 of the shaft and a ring 20 shrunk to the shaft. The dogs b are all in a plane perpendicular to the'shaft and the dogs a are arranged each within the plane of one of the gear wheels 3, 4 and 5. Thus dog 90. is to cooperate with wheel 3, dog Illa with wheel 4 and dog I la with wheel 5. All dogs may be sunk into recesses lb of the crankshaft. The dogs a may by turns be engaged with or disengaged from the gear wheels 3, 4 and 5, in a manner described hereafter, to permit by these wheels and the corresponding rims of the intermediate wheel I an 40 operative connection in a variable ratio between the pedalshaft and the chain wheel. The said wheels possess to this end six equally spaced notches 3a, 4a, 5a in the walls of their bores which are cooperating with the dogs a.

The dogs I) are controlled by springs: l3 which have the-tendency to expel the dogs from their recesses lb. A control disc I 2 surrounding all the dogs is arranged rotatably on the crankshaft V and possesses a curved recess l2c on its inner rim which at one end tapers into said inner rim and at the other end forms a shoulder l 2d. The cutout I2c permits the dogs b to be expelled from their recesses. These recesses are of such a form and size that they permit only one dog 55.

IOb at a time to be raised by its spring I3 from the respective cavity in the crankshaft into an elevated position and this only in the case when at the same time the corresponding dog Illa is freeto be raised into engagement with one of the notches 4a.

Said disk I2 is made of three plates pinned to- V I g'ether, to wit, ,two. outer plates IZa and I21) having ratchet "teeth on, their outer rim set in Co-' operating with these ratchet teeth is a stopplate.

opposite direction and a center plate I2.

I4 rotatably held on the countershaft and pr vided on its half of a largerl diameter with.

tooth I4a, while with its recessed half of smaller diameter it is located between two diametrically arranged stop pins I6, H, which permitifor' disk I4 only a small pivoting. movement large: enough to'throw tooth I4a alternatingly' in and out of gear with the ratchet teeth of control disk IZ'b; a Stop plate I4 carries also a spring-controlled pawl I5 which becomes engaged with the ratchet teeth of control disk I 2a when crankshaft is back pedaled in thedirection of; the arrow 28 asshown in ,Fig. 2,=while in Figr3 tooth- Ma and pawl I5 are shown out of engagement during the forward pedalingin the direction of arrow 21. During this forward pedaling, the stop plate I4 is stopped by pin IE and the pawl- 15 ratchets over the teeth IZa and I2b.-- Stop plate I4 shows besides onits smaller half a. circular recess Mb against which bears a spring-controlled arm I8. This arm locks stop plate I4 and with it also-control disk; I2 in the: speed-change position of Fig. 2 and the pressure of thespring-controlled arm I8 must be overcome toresume again the forward movement of the crankshaft. 1

The change-speed gear is operated as follows:"

We will suppose that the carrier pawl corresponding to gear wheel 4 be effective, that is that dog- Illa be engaged into one of the notches. 4a in the gear wheel 4. Then dog Iflb and disk I2 take the relative positionasshown in Fig.3, and.

also the parts' I4- and I5. It is desired to change the gear ratio into the next following step.

For this purposethe crankshaft must be backpedaledfor a quarter turn 'in an anti-clockwise directionas shown by arrow 28. Then control disc I2 will be taken along by friction will contactbytooth I2a with'pawl I5 and'turn the stop:

plate. I4 intothe position of Fig- 2. The control disk isthereby stopped; but the shaftI continues turning therefore the dog Iflb projecting into the cutout Il2c'will leave this rece'ssand-bepressed back into its recess Ibtogether with the corresponding'dog Illa which isalso sunk into its recess I?) of the crankshaft and is disengaged therefore from gear wheel14.- Now bythe-continued backpedaling dog I II) will take the place of dog I06 and come to face the recess I 2c and will be ex pelled by its spring I3 from its recess I b'of the crankshaft, when the cooperating dog Ila can i drop into a recess 5a of'the gear wheel 5. -If. this i dog does not face said recess, dog IlIb remains sunk within itsrecessll). I j y The crankshaft is'n'ow turned again in a. clockwise direction arrow-'21); and then the control:

. disk I2iwill be prevented,frornjturning likewise 1 by thetooth vI la, because arm I 8 ,has been engaged b'yfthenotchv I4b-of stop. plate I4. As soon as. dog. .Ilb bears against the'shoudler" I2dthe;

stop; plate I4 is brought back against the effect of arm I8 into'its first position shown in Fig. 3. The 'spacing ofthe notches 3a, 4a, 5a of the wheels: carried: by the crankshaft" amounts to about half the length of the arc of recess I20 so that in the above mentioned case, where after the change the succeeding dog a could not engage one of the recesses 3a, 4a, 5a, this engaging becomes possible during the clockwise rotation of the crankshaft.

If at the end of the back pedaling the control 7 disk I2 advances in sucha position with respect to the dogs I), in Whichthe dog facing the recess lie is kept sunk within its recess by the portion .ofthe cut out dying out into the bore, thisdog ll b'e'brought into engagement with the should'e'r IZdF :owin'g'to'the stopping of the control disk by the stop plate, when the shaft is again pedaled ina clockwise direction. In this position a com- 'p'l'et'e engagement of said dog a is always possible. I Thus-care h'as been. taken that in no case a dogdiately afterwards he disengaged again and sunk into its recess of the crankshaft. Only thefollowing dog h will be engaged with the shoulder I 2d by a stopping ofthe shaft. It is evident that according to the described structurerch ange-speed gears with two or with more than three" steps couldbe built. parts 'could loe formed otherwise than shown by the drawings without leaving the scope of the present invention. 1 What I claimis:

1.- Change-speed gear for bicycles of the constant meshtoothed Wheel type in which the speed change is obtained by back pedalling and in=com-' loinati'on a casing-adapted to be pressed into the framing; a pedalshaft Vand' a; countershaft, the

first rotatably heldi withi-n the casing, three Also the r change-speed pi'nions loose-on the pedal shaft and v having notched bores; one of 'saidpinions in oper-.

ative' connection with the chain wheel; a change Wheelsleeve l'oose on t-he countershaft and in constant'm'esh with said'change speedpinions, a con trol disk formedi'n part by two coupled coadjacent disks ha ving oppositely directed ratchet teeth and providedwi th a limited recess in its bore, three small'sha-ftssunkinto longitudinal grooves of the crankshaft; each small shaft carrying two dogs, the one, spring. contr'olled, adapted to'cooperate with: said recess in the bore'ofthe control disk and the oth'er adapted to cooperate'with the notches of one of'the-respective change-speed pinions; a toothed stop plate pivotally' held on said countersh'aft'; a sprin-g-co'ntrolled plate'car ried by thisstop plate whichstop plate andpawl. is arranged to: cooperate with the teeth of the controldisk, and. diametrically arrangeds'top pins fastto the casing adapted to limit the pivoting of said stop plate: and to :cause t-he engageme'nt 'of: one ofthe dogs with a notch of a respective changeespeed pinion.

. 2. In achange-speed gear according to claim I control. diskin a respective change speed position lsaid device comprising a circular. recessin therimof the stopplate and a spring-controlled arm-hinged to the-casing and adapted-tobe en- 'gaged' in said recess. 7

' EMILE BAUMGARTNER.

the combinationwith alocking device to lock said 

